EN
Efficacy of protection of winter wheat against pathogenic fungi causing many dangerous diseases depends to a high degree on environmental conditions in a given vegetative period. Thus monitoring their development while considering present meteorogical conditions in a related period makes it possible to determine a degree of endangerment of cultures by selected fungal species, and prevent their development. During the studies conducted in the Regional Experimental Station of Plant Protection Institute – National Research Institute Grodzisk Mazowiecki, on the fields of Agricultural Experimental Station SGGW Chylice, Mazowieckie voivodeship, a high differentiation of weather conditions was recorded, especially at the time of a high demand of plants for water (April–July). On leaves of winter wheat occured at the highest intensity septoria leaf spot (Septoria spp.) and tan spot (Pyrenophora tritici-repentis). However brown rust (Puccinia recondita) and powdery mildew (Blumeria graminis) did not present a particular danger. Ears of winter wheat were mainly colonized by S. nodorum, the causal agent of glume blotch. The occurence of ear fuzariosis (Fusarium spp.) and sooty moulds (Alternaria spp., Cladosporium spp.) was also dependent on weather conditions. On stem base of winter wheat eyespot (Tapesia yallundae) and fungi of Fusarium species presented the highest danger. All the above listed pathogens can be of a high endangerment for the amount and quality of winter wheat grain yield.